This twist involves the same issue uncovered this past November when prosecutors revealed a DNA test appearing to clear Gary in the Oct. 25, 1977, rape and strangling of Martha Thurmond was the result of laboratory contamination.

The same DNA profile developed from the Thurmond evidence showed up on a BB gun found after a 2011 shooting in Atlanta's Morningside neighborhood.

The suspect in that shooting, Michael Christopher Lloyd, does not match the DNA found on his BB pistol. Now 32, he was born three years after the last of the seven serial killings that occurred here between September 1977 and April 1978.

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Lloyd deepened the mystery when he told Gary's lead defense attorney he regularly kept the pistol in a 1970s-era surplus Army flak jacket he'd bought -- raising the possibility old cells in the jacket rubbed off on the gun.

Defense attorney Jack Martin's conjecture was that the jacket once belonged to a soldier stationed at Fort Benning back in the 1970s, who may have been involved in the stranglings.

But Martin said prosecutors claim the gun's DNA profile comes from the same Georgia Bureau of Investigation crime laboratory "control sample" that tainted the Thurmond evidence. The sample is a known DNA profile technicians use to test their equipment.

The defense motions mentioning the Lloyd case were filed July 6, 2012, but were sealed from public disclosure while authorities investigated the match.

They tell the story of two Atlanta men who had a long-running feud that led to the shooting. William Paul Garey, now 60, a resident of Greenland Drive, east of Atlanta's Piedmont Park, had sued Lloyd and got a restraining order against him.

According to court records and Atlanta news reports, someone fired a high-powered rifle through the rear of Garey's home around 12:50 p.m. April 20, 2011.

The noise was so loud Garey thought someone had thrown a bomb in his house. He and neighbors called police, who swarmed the area, set up a perimeter, called in a SWAT team and started hunting for the suspect, who witnesses said was wearing camouflage. Streets were blocked and schools in the area went on lockdown as the manhunt ensued.

In a few hours, police caught Lloyd, then 30, and charged him with aggravated assault. Finding his BB pistol behind Garey's house, they sent it off for DNA testing, which yielded the same profile as the Thurmond evidence.

Martin said Lloyd ultimately was diagnosed with schizophrenia and sent to a mental health facility in Savannah, where the attorney traveled to question him.

That's where Lloyd told him about the Army flak jacket.

The jacket has been held for evidence, said Martin, adding that a military historian dated the jacket's use to the mid-1970s or later.

"It wasn't similar to the one I had in Vietnam," Martin said. "That was a bulky one. Back then we had these really sort of thick things. It was truly the type of flak jacket that could have been used by a trainee or anybody at Fort Benning."

Martin has maintained other evidence from the serial killings does not fit Gary, including footprints, semen and teeth marks from a bite on a victim's breast. His motion to gain Gary a new trial is set for a hearing before Jordan on Feb. 10.

Prosecutors have said the GBI lab conducted further testing to confirm its contamination issue, which came to light when the control sample profile turned up in an unrelated case.

The discovery prompted the agency to require that all control samples be included in Georgia's DNA database, in case they matched evidence in other cases. That revealed the mysterious DNA profile from the Thurmond test was the control sample the GBI laboratory had been using. Lloyd's BB pistol was tested in that same lab, Martin said.

Prosecutors explained the mistake in court filings that refer to the Georgia Department of Forensic Sciences as the "DOFS":

"The DOFS investigation revealed that the quality control sample was used in the same work area the day before the testing on the Thurmond slide. It is believed that some equipment in the work area then contaminated the Thurmond slide."

Other evidence in the Thurmond slaying points to Gary, they wrote:

"In fact, Gary's fingerprints were found at the point where he entered her home, he gave a statement to detectives on the night of his arrest admitting to entering her home, he provided details that were not released to the public, and he even directed the detectives to the home."

A test of evidence from the Sept. 11, 1977, rape and beating of Gertrude Miller, which immediately preceded the seven serial killings that terrorized Columbus through the spring of 1978, also reportedly showed DNA that didn't match Gary.

Prosecutors have discounted that, saying it came from clothing Miller wore to the hospital but may not have been wearing when she was attacked. The items were a white sleeping gown, a white slip and underwear.

"The items tested relating to Mrs. Miller's case were not 'intimate items' such as vaginal swabs tested in other cases, which would be most likely to reveal the identity of the perpetrator," wrote District Attorney Julia Slater and Senior Assistant District Attorney Don Kelly.

They now maintain the only valid DNA test came from the Sept. 24, 1977, rape and strangling of Jean Dimenstein: "The semen found in the vaginal washings from victim Mrs. Jean Dimenstein positively matched which proves that Gary is guilty of the rape and murder of Mrs. Dimenstein."

The defense and prosecution agreed to the DNA testing on Feb. 19, 2010, three months after Gary was scheduled to die of lethal injection.

Besides Dimenstein, the stranglings for which Gary was not convicted were those of Ferne Jackson, 60, of 2505 17th St., on Sept. 15, 1977; Mildred Borom, 78, of 1612 Forest Ave., on Feb. 12, 1978; and Janet Cofer, 61, of 3783 Steam Mill Road, on April 20, 1978.

With conflicting results reported from the first DNA tests, Gary's defense team in 2011 sought additional testing on evidence from the rape and beating of Miller, 64, of 2703 Hood St.

Gary was never charged with Miller's assault, but Smith used it to show a pattern of criminal conduct and had Miller identify Gary as her assailant during his 1986 trial. Miller has died since.

In March 2012, the tests conducted by Bode Technology Group of Lorton, Va., found sperm cells on the slip Miller wore to the hospital yielded a partial DNA profile that did not match Gary.

With such evidence apparently favoring his client, Martin filed a motion seeking a new trial July 9, 2012, around the same time he filed the sealed motion regarding the DNA profile from the Atlanta shooting.